Default mode network and reward network dysconnectivity among young individuals with major depressive disorder with...

Area of Science:

• Neuroscience
• Psychiatry
• Medical Imaging

Background:

• Major depressive disorder (MDD) affects up to 30% of patients with low-grade inflammation (LGI).
• The impact of LGI on brain functional connectivity (FC), specifically the default mode network (DMN) and reward network, in young MDD patients is not well understood.

Purpose of the Study:

• To investigate the effects of LGI on the DMN and reward network's functional connectivity in young patients with MDD.
• To compare FC patterns between MDD patients with and without LGI, and healthy controls.

Main Methods:

• Resting-state functional connectivity (FC) magnetic resonance imaging (MRI) was performed on 161 young MDD patients and 112 healthy controls.
• MDD patients were categorized based on LGI criteria (C-reactive protein levels ≥3 mg/L), with 23 meeting the criteria.
• Seed-based connectivity analysis was employed to examine FC within the DMN and reward network.

Main Results:

• Functional dysconnectivity unique to MDD patients with LGI was observed in the DMN.
• Specific alterations included decreased FC between the medial prefrontal cortex (mPFC) and lingual gyrus, and between the right lateral parietal cortex and right angular gyrus/calcarine fissure.
• Increased FC was found between the mPFC and left cerebellum crus II, and between the left nucleus accumbens and right hippocampus/left anterior insula.
• MDD patients, irrespective of LGI status, showed increased intra-DMN connectivity, notably between the posterior cingulate cortex/precuneus and left lateral parietal cortex/right supramarginal gyrus.

Conclusions:

• Low-grade inflammation significantly influences both the default mode network and reward network in patients experiencing depression.
• These findings highlight LGI as a critical factor modulating brain network function in major depressive disorder.